Planar tubes



J. B. GAENZLE June 3, 1958 PLANAR TUBES Filed Sept. 13, 1955 INVENTOR JOHN B. GAENZLE BY ATTO NEY PLANAR TUBES John B. Gaenzle, Bay Shore, N. Y., assignor to Sylvania Electric Products Inc., a corporation of Massachusetts Application September 13, 1955, Serial No. 533,966

6 Claims. (Cl. 313-337) This invention relates to electron discharge devices.

In particular the invention relates to an electron discharge device comprising electrodes, including an indirectly heated cathode, mounted within an evacuated envelope for use where the device may be subjected to violent shocks or large accelerations.

It is an object of the invention to make the electron device rugged and yet provide for small inertia because of a reduction in mass of parts within the envelope which may move under shock or accelerative forces.

It is a further object of the invention to provide for means to maintain or restore internal parts to normal operative position when the device is subjected to shock or sudden changes in velocity.

It is another object of the invention to provide means whereby parts will seat properly and easily upon assembly of the device.

It is yet another object of the invention to increase the thermal efiiciency of the cathode by providing for only a small radiating area below the cathode and by reducing heat conduction through parts connecting the cathode with the lead-in conductor thereto.

These and other objects will be made clear after consideration of the following specification and claims when taken in conjunction with the accompanying drawing in which the figure represents a cross-sectional view through a cylindrical triode embodying the invention.

* ate-tit In said figure the triode 2 is represented as having an anode 4, a grid6, and a cathode S.

The cathode 8 comprises a conventional emissive coating 14 on a nickel or equivalent plate 16 which plate is afiixed to a metallic sleeve 18 as by welding the same to an outturned lip on the sleeve. Within the sleeve is aflixed an inverted cup 26 with perforated transverse wall, said cup being joined to the sleeve, preferably by welding. The transverse wall perforation has a downwardly turned lip forming a seat which supports sapphire head 22 or other insulator of like character. Within the sleeve and between the plate i6 and cup 20 is an in sulated heater 24. 1

The bead is axially perforated and a sleeve 26 traverses the perforatiointhe upperend of the sleeve being beaded over the insulator. The lower face of the in sulator is hemispherical and can move universally on its seat surrounding the opening in the cup 20. The bottom or transverse wall of the cup carries a zirconium washer 28 which serves as the getter forthe tube. The sleeve 26 is welded to a flexible rod 36 which always appliesa downward pull on the cathode assembly, as will be described. The sapphirebead not only serves as an electrical insulator but also as a means to heat insulate the lead-in 30 from the heater and adjacent portions. One end of the heater Wire is connected internally to the sleeve and through the rod 30 to an external connection while the other end of the heater wire is connected to the cathode 'cup 20 and to a metallic sheath 32, which forms a heater leg and cathode terminal of the device,

2,837,683 Fatentecl June 3, i958 "ice via a connector 34; The downward pull of the rod 30 forces the cathode plate 16 to rest on the circular perimeter of a thick ceramic washer 36. The washer is provided with a central bore in which the sleeve '18 lies, the sleeve being spaced from the walls of the bore to hinder heat transfer from sleeve to ceramic. The conductive sheath 32 also lies in an enlarged portion of this bore and is held in place thereon by suitable means, as solder 38.

The ceramic washer 36 is provided with a circular recess 40 in its upper face, said recess being semi-circular in cross-section. The recess is provided to increase the electrical leakage path from the cathode to other electrodes and to minimize heat dissipation from the cathode heater. There is also provided one or more radial slots 42 from recess 40 to the central bore to provide passages for evacuation of the envelope, as will be described, and to minimize contact of plate 16 with the ceramic material and thereby reduce heat transfer from cathode to ceramic.

Within the sheath 32 is positioned an insulating thick washer 44, hermetically sealed to the sheath by solder 46 and provided with a bore through which the rod 30 passes freely. The bore has an enlarged area in which is located a thimble 48 hermetically sealed to the insulator 44 by solder 50. The thimble has an opening in its cap portion registering with the bore in the insulator 44. Within the thimble is a spring 52 held in compression between the cap portion of the thimble and a washer 54 slidable within the thimble. The washer is centrally perforated to allow passage of the rod 30 therethrough and is further provided with one or more other perforations as at 56 to allow evacuation of the envelope.

Securedto the rod 30 immediately below the washer 54 is an enlargement in the form of a sleeve 58. In assembly of the triode, after all of the ceramic and metal parts of the tube had been made the sleeve 58 is thrust upwardly against the washer while the rod is held against motion thereby applying compression to the spring. While the spring is thus under compression, the sleeve is secured to the rod by crimping, welding, or otherwise. Due to spring action and the ball and socket connection provided between the bead 22 and its seat, the cathode plate 16 can adjust itself into proper engagement with the top face of the washer 36, and,during use, any violent forces tending to disarrange the cathode in the triode would be damped. Also parts, it shifted, would be restored to normal position due to the construction just described.

The rod 30 is prolonged beyond the sleeve 58 to a point where it extends into a terminal pin 60 conventionally secured to the rod, the rod being hermetically sealed as at 64 into a bulb 62 or other close off device of metal or ceramic. The bulb is hermetically sealed within the thimble 48 as by being brazed or welded thereto. Betweenthe seal 64 and the sleeve 58, the rod is bowed, as indicated at 66 in order to permit the coil spring 52 to function and yet retain the seal at 64. The bulb has a tubulation 67 communicating with its interior, his tubulation being utilized for exhausting the envelope, after which the tubulation is sealed off as at 68. The triode is provided with a protective cylinder 70 of ceramic material suitablymechanically connected to the sheath I 32, as by solder, and with a close off washer 72 of metal or ceramic material suitably held within the cylinder 70 and through which the rod 35] extends on its way into the pin 60. The cylinder 70, cover washer 72, and pin 66 are applied after evacuation of the triode and sealing off the tubulation at 68 have been efiected.

The grid 6 is a circular frame with parallel grid wires or rods extending across the opening in the frame, the frame bearing against a metallic washer 74 positioned is of a thickness to properlyspace the grid from the oathode. Abutting the upper surface of the grid is a second thick centrally .bored ceramic washer 76 in which bore is hermetically sealed the anode 4, as by a metal seal '78. The anode may comprise a short outer metallic shell 86 directly sealed to the washer 76. This shell is intended to serve as the anode terminal. Within the shell and in heat conductive relation thereto as by the use of soft solder is a solid copper rod 82 to the upper end of which is attached a series of heat radiating fins, not shown. In the manufacture of the tube the heating and bombardment of the electrode elements within the tube during exhaust to remove occluded gases in the electrodes is effected prior to afiixing the rod 82 within the sleeve 80 so that the sleeve could be raised to a suitable tem perature, not possible with the rod in position. Furthermore the heating and bombarding of the elements without the rod 82 in place precludes the possibility of the cup being cracked by rod expansion during heating. Of course during normal use of the tube, the solid upper rod 82 will withdraw heat from the cup, allowing for higher power operation of the tube and in higher ambient temperatures.

The grid is electrically connected to metallic sleeve 84 which holds the upper ceramic washer 76, grid 6, spacer 74, and lower ceramicwasher 36 in assembled relation, there being provided for this purpose a hermetic conductive seal 86 which not only holds the said parts in said assembled relationship but also provides said electrical connection between the grid and the sleeve 84.

The anode, grid, and cathode lie within a sealed chamber. Communication with said chamber for exhausting the same may be effected through a passageway beginning with the tubulation 67, the bulb 62, the opening or openings 56 in the washer 54, the opening in the cap of the thimble 48, the bore in thick washer 44, the space surrounding the sleeve 18 and the radial passageways 42.

Although I have illustrated the invention as being embodied in a triode, it will be realized after reading the claims that the invention is not necessarily restricted thereto since obviously the cathode structure herein claimed may be used in other relations.

Having thus described the invention, what is claimed is:

1. In an electron discharge device, a cathode plate having an electron emissive upper surface, an insulating support for the underlying face of said plate, a sleeve secured to said plate and extending downwardly therefrom, and being spaced from said support along a major portion of its length a seat carried by said sleeve, a rod having a pivoted bearing on said seat and extending downwardly therefrom and spring means coupled to the rod and reacting against a fixed part of the device ur ing said rod downwardly to bring the plate in secure engagement with the insulating support.

2. .In an electron tube, a cathode structure comprising an insulating support having a bore therethrough, a cathode plate over said bore having its peripheral portion resting on said support, a sleeve affixed to and depending from said plate and extending downwardly through said bore and spaced from the walls of said bore along a major portion of its length, a transverse wall in said sleeve having an opening therein forming a seat, an insulator pivotally supported on said seat, a rod attached to said insulator, and spring means coupled to the rod and reacting against a fixed part of the device for applying a force to the rod to urge the plate against its support. 3. A cathode structure comprising an insulating support having a bore therethrough, a cathode plate over 4 said bore having a peripheral portion resting on said support, a sleeve afiixed to and depending from said plate and extending downwardly through said bore, a transverse wall alfixed to said sleeve and having an opening forming a seat, an insulator rotatable on said seat, a rod attached to said insulator, a cathode heater in the cham ber defined by the walls of the sleeve, the plate and the transverse wall, an electrical connection between one terminal of the heater and the sleeve, an electrical conection, oetween the other terminal of the heater and the rod, and spring means coupled to the rod and reacting against a fixed part of the device for applying a force to the rod to urge the plate against its support.

4. A cathode structure comprising an insulating support having a bore therethrough, a cathode plate over said bore having a peripheral portion resting on said support, a rod having connection with said plate and extending in a direction axially of the bore, a first insulating washer held in spaced relation below said support, said rod passing freely through said first washer, an enlargement on said rod, a second washer bearing against said enlargement, and a spring between the first and second washers urging the plate against its support.

5. A cathode structure comprising an insulating support having a bore therethrough, a cathode plate over said bore having a peripheral portion resting on said support, a rod having connection with said plate and extending in a direction axially of the bore, a first insulating washer held in spaced relation below said support, a thimble bearing against said first washer, said first washer and thimble having registering openings with said rod passing freely through said registering openings, a sheath in engagement with said support and first washer forming an air tight chamber therebetween, a close off device sealed to the lower end of the thimble, said rod passing therethrough and forming a hermetic seal therewith, an enlargement on said rod, a second washer bearing against said enlargement, and a spring between the thimble and the second washer urging the plate against its support.

6. In an electron tube, a cathode structure comprising an insulating support having a bore therethrough, a cathode plate over said bore having its peripheral portion resting on said support, a sleeve aifixed to and depending from said plate and extending downwardly through said bore and spaced from the walls of said bore along a major portion of its length, a heater within said sleeve, a transverse wall in said sleeve having an opening therein forming a seat, an insulator pivotally supported on said seat, a rod attached to said insulator, and a spring, under compression, coiled about said rod and in spaced relation thereto, with one end of said spring bearing against a fixed part of the structure below the heater and with the other end connected to said rod.

References Cited in the file of this patent UNITED STATES PATENTS 1,744,796 Stuart Oct. 11, 1927 2,079,163 Gardner et a1 May 4, 1937 2,146,365 Batchelor Feb. 7, 1939 2,244,358 Ewald June 3, 1941 2,476,060 Moss July 12, 1949 2,558,357 Grimm June 26, 1951 2,647,218 Sorg et al. July 28, 1953 2,693,546 Sorg et al. Nov. 2, 1954 2,768,321 Peterson Oct. 23, 1956 FOREIGN PATENTS 57,193 Holland Apr. 15, 1946 

